Anti-cross threading device

ABSTRACT

The present invention permits a screw or male member to align prior to entering a threaded section and being driven. This alignment can avoid cross threading of the screw and the internal threads as often happens with power driven screws. The present invention generally includes a device with an unthreaded section and a threaded section. A screw or male member passes through the unthreaded section prior to entering the threaded section and causes the screw or male member to be aligned before being driven.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/662,736, filed Sep. 15, 2000, now allowed, which claims thebenefit of U.S. Provisional Patent Application No. 60/215,252, filedJun. 30, 2000.

BACKGROUND OF THE INVENTION

[0002] One problem that assemblers, machine builders, manufacturers,mechanics and the like have is cross threading internal threads. Whenassembling of devices was performed by hand, cross threading of internalthreads did not occur frequently. But, products are now increasinglyassembled using power devices. Cross threading occurs more frequentlywhen using powered devices such as electric screw drivers and powerguns.

[0003] Cross threading of internal threads can be especially problematicfor fixed devices and inserts as opposed to nuts. Once a device hasfemale threads and they become cross threaded, the device may beunusable. Cross threaded inserts can be extremely difficult orimpossible to remove or replace. Often, cross threading internal threadsmeans that the part needs to be disposed of which could be a very costlyproblem. Cross threading or the occurrences of cross threading need tobe reduced. Accordingly, there is a need in the art for a device whichreduces cross threading.

SUMMARY OF THE INVENTION

[0004] This need is met by the present invention, where an anti-crossthreading device is disclosed. The device includes an element, acylindrical cavity, an unthreaded section and a threaded section. Theelement has an exterior surface. The cylindrical cavity is in theelement extending from the surface to a first length. The cylindricalcavity has an interior surface. An unthreaded section of the interiorsurface extends from the element surface to a second length. Thethreaded section of the interior surface extends from the second lengthto the first length. Other devices and methods of fabrication aredisclosed. The present invention permits a screw or male member to alignprior to entering a threaded section. This alignment can avoid crossthreading.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]FIG. 1 illustrates a cross sectional view of a conventional screwand insert.

[0006]FIG. 2 illustrates a cross sectional view of a screw andanti-cross threading insert according to one embodiment of theinvention.

[0007]FIG. 3 illustrates an assembly utilizing anti-cross threadinginserts according to another embodiment of the invention.

[0008]FIG. 4 illustrates a cross sectional view a an anti-crossthreading element according to another embodiment of the invention.

[0009]FIG. 5 illustrates an anti-cross threading insert according toanother embodiment of the invention.

[0010]FIG. 6 illustrates a method for fabricating an anti-crossthreading device according to another embodiment of the invention.

DETAILED DESCRIPTION

[0011]FIG. 1 illustrates a screw 101 and a conventional insert 102. Theconventional insert has internal threads 103 extending from top tobottom. The screw 101 has external threads 104 which match the internalthreads 103 of the insert. The screw 101 is shown slightly mis-alignedwith respect to the insert 102. Any turning or driving of the screw 101will likely cause cross threading of the internal threads 103 or theexternal threads 104.

[0012]FIG. 2 illustrates a screw 201 and an anti-cross threading insert202 according to one embodiment of the invention. The anti-crossthreading insert 202 includes an unthreaded section 205 and internalthreads 203. The internal threads 203 correspond to the external threads204. The unthreaded section 205 is at least as wide as the majordiameter of screw 201. The screw 201 will not be misaligned before theexternal threads 204 encounter the internal threads 203 and thus,prevent cross threading of the internal threads 203 or the externalthreads 204. This contrasts to the prior art FIG. 1, where the screw 101should be aligned with the insert 102 prior to entering the insert 102to avoid cross threading of the internal threads 103 or the externalthreads 104.

[0013]FIG. 3 illustrates an assembly 310 utilizing anti-cross threadinginserts 202 according to another embodiment of the invention. Theanti-cross threading inserts 202 are inserted into the assembly 310 asshown. Another assembly or part (not shown) can be attached to theassembly 310 by driving a conventional screw (not shown) into at leastone of the anti-cross threading inserts 202.

[0014]FIG. 4 illustrates a cross section of an anti-cross threadingelement according to another embodiment of the invention. The element islocated or formed in a structure 401. The structure can be some type ofdevice or a sheet of material or any other structure that utilizesinternal threading. The element comprises an unthreaded section 406 anda threaded section 405. The unthreaded section has a length 407 and adiameter 402. The unthreaded section 406 is tapered at the surface inthis embodiment, but other embodiments may not have the unthreadedsection tapered. The threaded section has a length 408 and an innerdiameter 403 and an outer diameter 404 of the threads. The unthreadedsection 406 diameter is greater than or equal to the outer diameter 404of the threaded section 405. The unthreaded section length 407 andthreaded section length 408 can vary according to the application.Additionally, the inner diameter 403 and outer diameter 404 can varyaccording to the application. Further, the threads in the threadedsection are not limited to any specific size, style or shape of threads.

[0015]FIGS. 5A and 5B illustrate an anti-cross threading insertaccording to another embodiment of the invention. The exterior of theinsert includes a lip 516 and a lower portion 517. The lip 516 is at afirst end of the insert into which a screw may enter. When the insert isused in an assembly, the lip 516 remains outside the assembly and limitsthe depth the insert is seated prior to a screw being driven into theinsert. For this embodiment, the lip 516 has a length 510 ofapproximately 0.043 inches. The lip 516 has an outer diameter 512 of0.307-0.315 inches. The lower portion 517 is adjacent to the lip 516 andis located along the same axis. The other end of the lower portion 517is a second end of the insert. For this embodiment, the lower portion517 includes three knurls 505 having a diameter of 0.256-0.259 inchesand having a length 507 of 0.054 inches. The knurls 505 assist ingripping a base material. Between each knurl 505 is an unknurl sectionhaving a diameter 513 of 0.234 inches and a length 514 of 0.014 inches.

[0016] The insert 501 includes an interior having an unthreaded portion502 and a threaded portion 503. The unthreaded portion 502 allows ascrew to be aligned prior to entering or driving into the threadedportion 503. The unthreaded portion 502 is located at the first end ofthe insert. The unthreaded portion 502 has a length of 0.100 inches inthis embodiment. Typically, the unthreaded portion 502 has a length ofapproximately 2 to 3 threads. For this embodiment, the unthreadedportion 502 has a diameter of 0.195 inches. Additionally, the unthreadedportion 502 includes a chamfer 504, a shallow angled cut, at the firstend of the insert. The chamfer 504 has a 45 degree angle cut. However,other angles and sizes may be used for the chamfer 504.

[0017] The threaded portion 503 is axial and adjacent to the unthreadedportion 502 and ends at the second end. The threaded portion 503includes internal threads. For this embodiment, the threads of thethreaded portion 503 are STD national threads form class 2B fit. Thethreads are 10-32 threads and have a maximum eccentricity betweeninternal and outer diameters of 0.002 T.I.R. The insert 501 has a lengthof 0.370 inches from the first end to the second end.

[0018] In this particular embodiment, the insert 501 is comprised ofbrass. Other embodiments may utilize other materials such as aluminum,steel, plastic and the like. The insert 501 may prevent or reduce theoccurrence of cross threading of internal threads.

[0019]FIG. 6 illustrates a method for fabricating an anti-crossthreading device according to one embodiment of the invention. A blockof material is provided at 601. The block of material can be an insert,nut, sheet of material or the like. Exterior features of the anti-crossthreading device are formed on an outer surface of the block at 602. Theexterior features can include a head, shank, knurl and the like. Acylindrical cavity is formed in the block of material at 603. Thecylindrical cavity has a first diameter and a first depth. The firstdiameter is selected according to thread size. The first depth isselected to allow a screw or threaded male member to be securelyattached to the anti-cross threading device. The cylindrical cavity iscounter bored to a second depth and a second diameter forming anunthreaded section at block 604. The second depth is less than the firstdepth and the second diameter is greater than or equal to the firstdiameter. A chamfer may be bored into the unthreaded section at block605. Threads are created in the remaining area or threaded area of thecavity at block 606. The threads can be created by tapping. The threadedarea is the portion of the cylindrical cavity that is not counter bored.

[0020] Having described the present invention in detail and by referenceto various embodiments thereof, it will be apparent that modificationsand variations are possible without departing from the scope of theinvention. The described embodiments and variations can be used toreduce the occurrence of cross threading and can properly align screwsprior to setting screws. They may prevent screws from being inserted atan undesirable angle. They may also increase the speed and quality withwhich devices are manufactured. The embodiments and variations areespecially helpful when power tools such as power guns are being used todrive screws into internal threads. The various embodiments can be usedin the case of inserts in molded thermoset and thermoplastic plasticparts. The various embodiments can also be used in other materials whichrequire threaded holes and are not limited to inserts.

What is claimed is:
 1. An anti-cross threading insert comprising: acylindrical housing having an interior surface, an exterior surface, afirst end and a second end; a gripping section disposed on at least aportion of said exterior surface; an unthreaded section formed on saidinterior surface at said first end; and a threaded section formed onsaid interior surface from said unthreaded section to said second end.2. An anti-cross threading insert according to claim 1, wherein saidgripping section comprises a plurality of knurls.
 3. An anti-crossthreading insert according to claim 2, wherein said plurality of knurlscomprises three knurls.
 4. An anti-cross threading insert according toclaim 1, wherein said unthreaded section includes a chamfer adjacentsaid first end.
 5. An anti-cross threading insert according to claim 4,wherein said chamfer is cut at an angle of approximately forty fivedegrees.
 6. An anti-cross threading insert according to claim 1, whereinthe diameter of said unthreaded section is greater than the outerdiameter of the threads of said threaded section.
 7. An anti-crossthreading insert comprising: a cylindrical housing having an interiorsurface, an exterior surface, a first end and a second end; anunthreaded section formed on said interior surface adjacent said firstend; and a threaded section formed on said interior surface adjacentsaid unthreaded section, said threaded section defined by threads withan inner diameter and an outer diameter such that said unthreadedsection has an outer diameter greater than said outer diameter of saidthreads.
 8. An anti-cross threading insert according to claim 7, whereinsaid unthreaded section has a length corresponding to 2 to 3 threads ofsaid threaded section.
 9. An anti-cross threading insert according toclaim 7, wherein said unthreaded section has a length of approximately0.100 inches, and said threaded section has a length of approximately0.270 inches and contains 10-32 threads.
 10. An anti-cross threadinginsert according to claim 7, wherein said exterior surface is at leastpartially defined by a gripping section.